Telephony.



E. R. CORWIN.

TELEPHONY.

APPLICATION FILED JULY 30.1915.

Patented May 30,1916.

4 SHEETS-SHEET I.

LINES 1 TO 500 LINES 501 TO 1000 ATTORNEY 'I'HB COLUMBIA PLANOORAPH 330.. WASHINGTON, D. c.

, E. R. CORWIN.

TELEPHONY.

APPLICATION FILED JULY 30, 1915.

1,185,376, I Patented MayBO, 1916.

4 SHEETS-SHEET 2.

F IG. 2 INVENTOR ELMERR. C ORVIN.

THE COLUMBIA PLANOGRAPH co., WASHINGTON, D. C.

E. R. CORWIN.

TELEPHONY. APPLICATION. FILED JULY 30. 1915.

Patented May 30, 1916.

4 SHEETS-SHEET 3.

FI 3 INVEl ITOB.

ELMER R.COKVI1\I ATTORNEY THE Conummpumoampu co., WASHINGTON, D. C.

E. R. CORWIN.

TELEPHONY. 1,185,376 APPLICATION FILED JULY 30, 19.1.5-

30 I 4 SHEETS-SHEET 4- E73 ,H k g FIG. 4

IINYENTOB ELMER R. C ORWIN ATTORNEY THE COLUMBIA PLANOGRAPH .ca, WASHINGTON, D. C.

ED STATES PATENT ELMER R. CORWIN, OF CHICAGO, ILLINOIS, ASSIGNOR T0 FRANK B. COOK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONY.

Specification of Letters Patent.

Patented May 30, 1916.

Application filed July 30, 1915. Serial No. 42,708.

To all whom it may concern citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephony, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part.

of this specification. Y

My invention relates to telephone exchange systems and has been embodied in a system whose telephone lines are divided into groups with exchange operators equipment at a plurality of operators positions and a calling line operated distributer switch for each group of lines and common to the lines of such group for associating the equipment of any of the operators, available, with the calling line employing it. These groups of lines have been divided into minor groups, the lines of each minor group having line switches which are preferably less in number than the lines of such minor group. Each group of line switches has been provided with a master switch in interchangeable relation therewith for determining the switch that is to be used. Other switches have been added for extending calling lines beyond the aforesaid line switches, these additional line extending switches bemg less in number than the first switches and divided into as many groups as there are major groups of lines, the added line extending switches of each group of such switches pertaining toa major group of telephone lines having associated .therewith facility for establishing their vassociation with an operator, the switches of one group being adapted for association with one operator, the switches of another group for association with another operator, etc.

The system in which my invention has been embodied has also employed a plurality of holding switches for each operator (each holding switch relating to a different major group of telephone lines) and a call distributer switch for each major group of telephone lines whereby any holding switch may be associated with any calling line in any group so that all calling lines may have access to any operator. The various line switches and line extending switches may be operated by calling subscribers through the intermediation of the holding switches and each operators telephone may be brought I into interchangeable association with her holding switches by means of automatically operating switching mechanism.

My present invention employs many features of novelty in the system above generally described and other features of novelty which are not to be limited to such a system,

the preferred embodiments ofthese features of the invention being fully hereinafter set forth in the specification and claims and are illustrated in the accompanying drawings, in which Figures 1 and 2, taken collectively, diagrammatically outline the preferred embodiment of the invention; and Figs. 3 and 4, taken collectively, illustrate one form of the invention as it may be practised.

Like parts are indicated by similar characters of reference throughout the different figures. j

I have chosen a thousand line exchange to demonstrate the manner in which the invention may be practised, Figs. 1 and 2 generally illustrating such an exchange. The lines are subdivided into major groups, there being five hundred linesin each major group in the example chosen. Each major group is subdivided into minor groups of preferably a hundred lines each. In Fig.

1 of the drawing two lines of each hundred line minor group are illustrated. The lines in the first minor group of the first major group may be numbered 1 to 100; the second minor group, 101 to 200, etc., as indicated in Fig. 1. The lines in the first minor group of the second major group may be numbered 501 to 600; the second minor group 601 to 700, etc.

The substation equipment may be of any suitable common battery type, each substation having a telephone switch hook 1, a telephone 1 receiver 2, a telephone transmitter 3, a call bell 4, and a condenser 5. Each line has a line relay 6, the line relays of the lines of each minor group having switch contacts that are in common connection with a line switch driving relay 7 which is thus common to the lines of the minor group to which it pertains. This relay 7 is in controlling relation to a master line switch 8 that is inclividual to the relay 7, there thus being one master line switch 8 for each minor group of lines and which master line switch is common to the lines of its minor group. The wipe-rs of the switch 8 are provided with sets of waiting contacts, preferably ten, though but five sets are shown in Fig. 1. Each set of waiting contacts is-individual to a line switch 9, there thus being ten such line switches for each minor group of one hundred lines, though Fig. 1 of the drawing illustrates but five switches for the sake of simplicity of illustration. The wipers of each master switch normally rest upon some waiting contacts and place the line switch to which .such contacts are individual in condition for operation. In the embodiment of the invention illustrated the operation of such line switch that is thus placed in condition for operation is effected by a calling subscriber in the minor group having such line switch, the operation of this switch continuing until the wipers thereof engage the waiting contacts pertaining to the calling line, it being understood that the wipers of each line switch 9 are provided with as many sets of waiting contacts as there are lines in the minor group to which such line switch belongs whereby each line switch may have access to each of the lines in the minor group of lines having such line switch. I do not wish to be limited, however, to the places at which the line switches have their operation initiated and controlled.

The wipers of each line switch 9, in addition to having a set of waiting contacts in the associate switch 8, also have a .set of waiting contacts in each of thirty line extending switches 10 assigned to the major group having such line switch 9, the similarly positioned waiting contacts in the .groups. Figs. 1 and 2 show six switches 10 (instead of the complete quota of fifteen) of each group of thirty in association with each operators position. The set of wipers in each switch 10 is represented by a set of waiting contacts in a call holding switch 11.

There may be two such switches 11 pertaining to each operators position A, B, one of these switches 11 at an operators position having waiting contacts pertaining to of fifteen line extending ing switches 10 relating to the other major j group of five hundred lines. By this arrangementeach operator has access to all of the lines in both major groups. A call distributer switch 12 is provided for each major group of lines (each such switch 12 having the relationship of a master switch to one group of line extending switches 10 belonging to each major group of telephone lines, this relationship being effected through the intermediation of the holding switches 11 to whichthe switches 12 also occupy the relationship of master switches) the wipers of each switch 12 having as many sets of waiting contacts as there are operators positions, two in the example chosen. By this switch 12 a calling line in either major group may be associated with either operator. The upper set of waiting contacts of the upper switch 12 is individual to the upper switch 11 of operator A and the lower a set of waiting contacts of the upper switch 12 is individual to the upper switch 11 of operator B. The upper set of waiting contacts of the lower switch 12 is individual to the lower switch 11 of operator A and the i lower set of waiting contacts of the lower switch 12 is individual to the lower switch 11 of operator B. As the invention is preferably practised, the wipers of the call distributer switches 12 normally rest upon a i set of waiting contacts. WVhen a call distributer switch 12 is associated with a calling line in the major group having such switch 12 (an association which is effected by the relay 7 employed by the calling line), said switch 12 associates a holding switch 11 of one operator with such calling line. The line extending switch driving relay 13 individual to such employed switch 12 effects the operation of relay equipment (diagrammatically indicated at 14 in Fig. 2) individualto the call holding switch 11 of one operator that has become associated with the calling line in the major group having such employed switch 12. Mechanism of such relay equipment 14: causes the other switch 12 to associate a holding switch 11 of the other operator with lines of the other major group, by which arrangement lines of either major group are not deprived of access to anoperator.

The operators are provided with holding relay selector switches 15 for coupling employed holding switches 11 with their tele phone equipments. The wipers of the switches 11 are normally resting in connection with some set of waiting contacts individual to some switch 10. The relay 13 pertaining to the employed switch 12 operates through the call holding switch 11 that is now coupled with the employed switch 12 to set the switch (individual to the set of waiting contacts engaged by the wipers 'after mechanism of relay equipment 14;

serves to hold the calling line until the switch 15 is moved to couple the employed switch 11 with the operator having it. The two call holding switches 11 provided for each operator are associated with the thirty links provided for the use of such operator, each link desirably having normally separated sections 16, 17. These links have their sections 16 connected with the wipers of the line extending switches 10, a group of these line extending switches pertaining to each major group of lines being represented by some of the links in each operators position. The links are shown as terminating in connecting plugs 18 adapted for insertion within spring jacks 19 that pertain to called 7 lines or other calling line extensions, though the invention is not to be limited to this form of termination for the links. Each link connector may be provided with a lamp 20 to designate it for use while each operator may be provided with a signal device 21 to attract her attention in the event of her absence from her position. Each operator may also have a key 22 for joining the separated sections of the employed links.

When the switch 15 has become associated with the employed holding switch 11 and when the calling line has been extended by the operation of the employed switch 10, the operators telephone set is connected with the calling line. Having ascertained the number of the line that is to be called, the operator will insert the plug 18 individual to the glowing lamp 20 in the jack 19 of the wanted line, whereafter the operator will manipulate the manual switch 22 to connect the employed link sections 16, 17. An established connection between calling and called lines thus includes waiting contacts pertaining to the calling line, the wipers of an employed switch 9 engaging these waiting contacts, the waiting contacts of the employed switch 10 that are connected with the wipers of the employed switch 9,

the wipers of the employed switch 10, the employed link '16, 17, the connecting plug 18 individual to the employed link, and the jack 19. I

The apparatus which is employed in performing the operations generally described in connection with Figs. 1 and 2 is illustrated in diagrammatic detail in Figs. 3 and 41 wherein I have illustrated two telephone lines included in the same minor group. hen a calling subscriber initiates a call he removes his receiver 2 preparatory to securing connection with some idle operator to extend the calling line into connection with the called line or some other calling line extension. The switch hook from which the receiver has been removed establishes a circuit traceable from the common grounded battery 23 (whose illustration is repeated for the sake of simplicity), through the re sistance coil 24, say of one hundred ohms resistance, the upper armature switch of the cutoff relay 25 and its contact, both sides of the telephone line by way of the switch hook, receiver and transmitter at the calling station and the alternate contact of the switch hook, the lower armature switch of the cutofl? relay 25, the winding of the line relay 6, to ground. The lower armature switches of the line relay 6 are grounded and the contacts of these armature switches that pertain to the lines of a minor group that includes the calling line are connected with the contact of the armature switch of relay 26 that is common to the lines of such minor group, there being one such relay 26 for the lines of each minor group. lVhen the line relay 6 of the calling line is energized, a circuit is established traceable from its lower and grounded armature switch, through the contact of such switch, the armature switch and contact of said relay26, the line switch driving relay 7 to the grounded battery 23. The relay 7 thereupon attracts its armature switch to establish a circuit traceable from the common grounded battery 23, the line switch interrupter 27. the armature switch of this interrupter 27 and its contact, the armature switch of energized relay 7 and its contact, the upper armature switch of the deenergized relay 28 and its contact, the top wiper of the master line switch 8 and the waiting contact engaged thereby, the motor magnet 29, to ground. The motor magnet is operated to turn the wipers of the switch 9 into engagement with the waiting contacts belonging to the calling line if such wipers are not already in such engagement. lVhen the wipers of the switch 9 thus encounter the waiting contacts of a calling line a circuit for stopping the motor magnet 29 is established, this circuit being traceable from the grounded battery 23, the winding of relay 28, the next to the top wiper of the master line switch 8, the waiting contact engaged by this wiper, the bottom wiper of the employed switch 9, the waiting contact engaged by this wiper, the upper armature switch of energized line relay 6 belonging to the calling line and its engaged con tact, to ground. The relay 28 is now energized to open a circuit for the motor magnet 29 at the uppermost armature switch of said relay. Another circuit is established which is traceable from the lowermost grounded armature switch of relay 28 and its now engaged contact, the intermediate armature switch of deenergized relay 30 and its contact, the winding of relay 31, to the grounded battery 23. The relay 31 establishes a circuit traceable from its upper and grounded armature switch, the

- tact engaged by this switch, the bottom wiper of the lower call distributer switch 12 and the waiting contact engaged thereby, the relay 30 of this switch 12, to the grounded battery 23. The energized relay 30 establishes a circuit traceable from the grounded battery 23, the motor magnet 34 of the lower switch 12 (the upper switch 12 pertaining to the major group that includes the minor group partially illustrated in Fig. 3, while the lower switch 12 pertains to the other major group), the armature switch of this magnet and its contact, the bottom armature switch of relay 35 and the normal contact thereof pertaining to the lower switch 11 (the two switches 11 illustrated pertaining to one operator), the two normally engaged left hand contacts of the manual switch or key 36 (usually governed by achief operator) to ground. The wipers of the lower switch 12 are moved by the motor magnet 34; into connection with the waiting contacts pertaining to the lower holding switch 11 in the next idle operators position. The upper call distributor switch 12, which is associated with the calling line, being in association with the upper call holding switch 11, cooperates with this latter switch in cans ing the calling line to become connected with the wiper of some line extending switch 10, the line extending switch employed having its wipers associated with the said switch 11. The motor magnet 37 of such switch 10 is operated to move its wipers into connection with the contacts that are connected with the wipers of the switch9 that is connected with the calling line unless the wipers of such switch 10 happen already to be connected with the Waiting c ntacts that e to the uppermost wiper of the upper switch l2 and the waiting contact engaged there by, the upper armature switch of relay 38 and its contact (belonging to the upper switch 12), the lower armature switch of relay 31 and its contact (belonging to the upper switch 12), the armature of the interrupter 39 and its contact (belonging to the upper switch 12), the winding of said interrupter, to the grounded battery 23.

The motor magnet 37 will operate to move the wipers of the employed switch 10 until they engage the waiting contacts that are connected with the wipers of the employed switch 9 and inasmuch as the wipers of the switch 9 are now connected with the calling line, such calling line is extended into connection with the wipers of the employed switch 10 inasmuch as the motor 37 will cease operation when this connection has been established. The circuit by which the motor magnet 37 is caused to cease operation is traceable from the grounded battery 23, the winding or relay 38 pertaining to the upper switch 12, the intermediate wiper of this switch 12, the waiting contact engaged by this wiper,'the third from the bottom of the wipers pertaining to the upper switch 11, the waiting contact engaged by this wiper, the bottom wiper of the employed switch 10, the waiting contact engaged by this wiper, the bottom wiper of the switch 8, the upper armature of the relay 6 and its contact, to ground. The circuit for the motor magnet 37 is thus broken at the upper armature switch of the energized relay 38 that belongsto the upper switch 12. The lower armature switch of the energized relay 38 pertaining to the upper switch 12 establishes a circuit traceable from ground, through the five hundred ohm resistance 40, the lower armature switch of said relay 38, the contact engaged by this armature switch, the upper armature switch of the associate relay 30, the contact engaged by this armature switch, the next to the bottom wiper of the upper switch 12, the contact engaged by this wiper, the upper winding of relay 35 belonging to the upper switch 11, the battery 23, to ground. The latter relay being energized, establishes a circuit traceable from the grounded battery 23, through the upper winding of this relay 35, (of preferably two hundred fifty ohms resistance), the top armature switch of this relay 35, the contact engaged thereby, the top armature switch of the associate relay %1, the contact engaged by this latter armature switch, the third from the top wiper of the upper switch 11, the contact engaged by this wiper, the top wiper of the employed switch 10, the waiting contact engaged by this wiper, the top wiper of the employed switch 9, the waiting contact engaged by this latter wiper, both sides of the calling line and the telephone receiver, transmitter and switch hook at the calling station, the next to the top wiper of the employed switch 9 by way of the waiting contact engaged thereby, the next to the top wiper of the employed switch 10 and the waiting contact engaged thereby, the fourth from the top wiper of the upper intermediate armature switch of the relay 41 pertaining to the upper switch 11, the contact engaged by this armature switch, the next to the top armature switch of the associate relay 35, the contact engaged by this switch, the lower winding of this relay 35, to ground. The five hundred ohm resistance 40 pertaining to the upper switch 12 being also in parallel with the lower winding of relay 35, shunts a suflicient amount of current through this relay to maintain it energized. The relay 35 under discussion establishes a circuit traceable from the grounded armature switch shown immediately above the core of this relay, the contact of this armature switch, the fourth from the bottom wiper of the upper switch 11, the waiting contact engaged by this wiper, the lower intermediate wiper of the employed switch 10, the waiting contact en- 'gaged by this wiper, the winding of relay 42 (individual to the employed switch 9) the lower intermediate wiper of the employed switch 9, the waiting contact en gaged by this wiper, the winding of the cutoff relay 25 individual to the calling line, to the grounded battery 23. The cutoff relay 25 pertaining to the calling line is now energized to open circuit through the line relay 6 of the calling line. The circuit established through the lower armature switch of this relay 6 is opened to open the circuit of relay 7 whose armature switch is released to open the circuit previously traced through the interrupter 27 and the motor magnet 29 pertaining to the employed switch 9, whereby the wipers of the employed switch 9 are permitted to remain in connection with the calling line. The relay 42, being in the circuit through which the cutoff relay 25 of the calling line is energized, attracts its armature switch to establish a circuit traceable from ground, through this armature switch, the contact engaged by the armature switch, the lower wiper of the master line switch 8 and the waiting contact engaged thereby, the winding of relay 26, the battery 23, to ground. The bottom armature switch of relay 26 establishes an apparent circuit for the motor magnet 43 pertaining to said switch 8, whereby the wipers of this switch are moved from as sociation with the employed switch 9 into association with some idle switch 9, the movement of the wipers of the switch 8 continuing until the bottom wiper of this switch engages a waiting contact that is disconnected from ground at some deenergized relay 42.

The same interrupter 27 which was previously associated with the employed switch 9 is now associated with the new switch 9 preparatory to taking part in effecting the operation of this new switch when another call in the same minor group is initiated. By this arrangement I make the interrupter 27 common to a plurality of line switches 9 that pertain to the same minor group of telephone lines. The next to the bottom armature switch of the energized relay 35 pertaining to the upper switch 11 establishes a circuit traceable from ground, through this armature switch, the contact engaged thereby, the bottom wiper of the upper switch 12 and the contact engaged thereby, the relay 30, the battery 23, to ground. The bottom armature switch of relay 30 establishes an operating circuit for the motor magnet 31 pertaining to the upper switch 12 which is traceable from the grounded bat tery 23, the winding of said motor magnet, the armature switch and switch contact of this motor magnet, the bottom armature switch of the associate relay 30 and the contact engaged thereby, the bottom armature switch of the relay 35 pertaining to the upper switch 11, the normal contact of this armature switch, the two left hand contacts of the button 36 pertaining to the upper switch 11, to ground. Said motor magnet 34 is operated to bring the wipers of the upper switch 12 into connection with the new set of waiting contacts pertaining to an idle switch 11, these wipers being maintained in such connection since the circuit for the circuit closing relay 30 will be broken at the next to the bottom. armature switch of relay 35 pertaining to such idle switch 11. The switch 11 thus newly associated with the upper switch 12 efl'ects the association of the interrupter 39 of the upper switch 12 with the motor magnet 37 of a new line extending switch 10 whereby an interrupter is made common to all of the motor magnets 37 pertaining to a major group of telephone lines. As will be understood from the description previously given, there is a switch 11 individual to each'major group of lines at each operators position and if both of these switches '11 pertaining to a major group of lines are busy the circuit of the driving magnet 34 will be opened at the bottom armature switch of the relays 35 pertaining to these two switches 11 so that the wipers of the upper switch 12 will remain in engagement with the waiting contacts pertaining to the switch 11 last selected, this engagement continuing if the switch 1.1 last selected is the first to be released, but being broken if the converse is the case to associate wipers 12 with the other switch 11 that is released. The switch 11 that has become associated with the calling line is employed to bring the calling line into connection with the operator having such switch 11 and if the wipers of the holding relay selector switch 15 are not already connected with the employed switch 11 they are brought into connection therewith due to the establishment of a circuit at the upper armature switch of relay 33 of such switch 11, this circuit being traceable from the grounded battery 23, the winding of relay 44, the upper armature switch of the previously 7 energized relay 33 (pertaining to the employed switch 11) the contact of this armature switch, to ground. The relay 44 establishes a circuit for the motor magnet 45 of the switch 15 which is traceable from the grounded battery 23, the winding of the magnet 45, the armature switch and contact of this magnet, the armature switch of relay 44 and its contact, the lower armature switch of the relay 46 and its contact, to ground. lVhen the wipers of the switch 15 have become connected with an employed switch 11, the operation of the motor magnet 45 ceases owing to the energization of relay 46 whose circuit that is thereupon established is traceable from the grounded battery 23, the winding of relay 46, the bottom wiper of switch 15 and the waiting contact engaged thereby, the alternate contact of the bottom armature switch of relay 35 belonging to the employed switch 11, said armature switch, the left hand pair of contacts belonging to the key 36 pertaining to the employed switch 11, to ground. The energized relay 46 stops the magnet 45 by breaking the circuit for this magnet at the contact of the bottom armature switch of relay 46. The upper armature switch of re lay 46 establishes a circuit traceable from ground through this armature switch, the contact engaged thereby, the lower intermediate wiper of the switch 15, the contact engaged by this wiper, the armature switch immediately beneath the core of relay 35 pertaining to the employed switch 11, the contact of this armature switch, the winding of relay 32, to grounded battery 23. The relay 32 of the employed switch 11, being energized, opens a circuit for the relay 33 at the bottom armature switch of such relay 32, the upper armature switch of the relay 33, thus deenergized, opening the circuit for the relay 44 belonging to the employed switch 15 to prevent the magnet 45 from operating when the'relay 46 is deenergized. The lower armature switch of said deenergized relay 33 removes ground from the bottom waiting contact of the lower switch 12 to allow the wipers of this lower switch 12 to stop in connection with the lower switch 11 pertaining to the operator having the aforesaid switch 15 so that another call. can lay in upon this operators position while the operator is taking care of the call about which she is receiving information through the upper switch 11.

If the exchange should be of larger capacity than that chosen as an example, each operator would have more than two holding switches 11 and in such event each relay 33 would have one armature added for each additional switch 11 supplied to each operator, the circuit environment of each added armature being similar to that illustrated at the bottom armature switch of each illustrated relay 33. If it should be desired to throw any switch 11 out of service the butten 36 individual thereto may be depressed by a chief operator to a locking position, thereby removing the ground at this button whose aid is required for the employment of the switch having thebutton, the ground being transferred to the right hand contact of the switch 36 which is connected with the bottom waiting contact of the associate switch 12 whereby said associate switch 12 cannot have its wipers stopped upon waiting contacts that belong to the switch 11 whose button 36 is thus depressed. Relay 46 is now energized and establishes, at its lower armature switch, the illustrated local circuit for the signal 21 individual to the selected operator to attract the attention of this operator if she is not at her position. The operators head telephone 52 is brought into telephonic circuit with the two top wipers of the employed switches 15, 10 and 9 and the third and fourth wipers from the top of the employed switch 11, whereby the calling subscriber may talk to the selected operator. The battery current for the calling. subscriber is furnished from the battery 23 by way of the windings of the relay 35 of the employed switch 11. The operators transmitter 53 is connected with the two terminals of the impedance coil 56, the transmitter circuit including a primary coil 57 that is in inductive relation with the secondary 58 which is included in the circuit of the head telephone 52. The condenser 59 is in bridge of the transmitter circuit to prevent the telephonic currents from being shunted from the line by the impedance coil 56. Condenser 60 is included in circuit with the operators head telephone to prevent the passage of battery current therethrough.

Each holding switch 11 is provided with a group of waiting contacts pertaining to the next to the top wiper thereof, each of these waiting contacts being individual to a diflerent link connector signal 20. When the relay 32 of the employed holding switch 11 is energized it establishes a circuit for the of the relay 68, the normal contact of this armature switch, the lamp 20 of the link thus coupled with the employed switch 11, the battery 23, to ground. The operator, having ascertained the number of the wanted line, will insert the plug 18, which is individual to the glowing lamp 20, in the jack 19 belonging or pertaining to such wanted line.

The operator will depress the button 22 to establish a circuit traceable from ground, the contacts of the button 22, the live hundred ohm resistance 67, the closed upper armature switch of energized relay 32 belonging to the employed switch 11, the top wiper of this switch and the waiting contact engaged thereby, the top winding of relay 65, the battery 23, to ground. This five five hundred ohm resistance 67 being also in parallel with the lower winding of relay 65 by way of the calling line, shunts a sufiicient amount of current through this relay to maintain it energized whereby the sections 16 and 17 of the link connector to which the relay 65 is individual are joined. The middle armature switch of relay 65 maintains the relays 25 and 42 connected with the calling line.

As another consequence of the energization of the relay 65, and under the assumption that the desired line is, idle, a circuit is established for the ringing control relay 68 which is traceable from the grounded battery 23, the next to the bottom of the armature switches of relay 65 and the contact engaged by this armature switch, the bottom armature switch of the busy test relay 69 (which is not energized if the called line is idle)- and its normal contact, the winding of relay 68, the second from the top of the wipers of switch 11 and the contact engaged thereby, the bottom armature switch of relay 32 and its engaged alternate contact, the bottom armature switch and associate relay 35 and its alternate contact, the normally engaged pair of contacts of the associate switch 36, to ground. The top armature switch of energized relay 68 establishes a'-- locking circuit for this relay which is traceable from the grounded battery 23, the next to the bottom of the armature switches of energized relay 65 and the contact engaged by this armature switch, the bottom armature switch of the busy test relay 69 and its normal contact, the winding of relay 68, the top armature switch of this relay,

the alternate contact engaged by this armature switch, the armature switch of relay 7 0, the normal contact of this armature switch, to ground. After the employment of the switch 11 in the process of extending a call ing line, such switch is moved into association with a new and idle switch 10 and a new and idle link connector and its lamp 20, a result which is due to the establishment of a circuit traceable from the grounded battery 23, the relay 41 of this switch 11, the bottom wiper of this switch and the waiting contact engaged thereby, the bottom armature switch of the relay 65, the contact engaged thereby, to ground. The energized relay 41 establishes a circuit traceable from the grounded armature switch immediately below the core of this relay, the contact engaged by this armature switch, the armature switch and contact of motor magnet 71 of the switch 11 under discussion, the winding of this motor magnet, to the grounded battery 23. This motor magnet 71 operates until the bottom wiper of said switch 11 encounters a waiting contact which is un-' grounded at the bottom armature switch of some deenergized relay 65 pertaining to an unemployed line extending switch 10 and .the link connector 16, 17 18 individual to such line extending switch. The relay 41 of said switch 11, by attracting its two top armature switches, breaks the bridge connection by way of the relay 35, which was included across the connection established between the calling subscriber and the selected operator whereby such operator is excluded from connection with the calling subscriber. The feeding of battery to the calling line, which occurred by way of the relay 35 when the operator was connected with the calling line, is effected, after the exclusion of the relay 35 from circuit, by way of the battery feed relay 65. Restored armature switches of the deenergized relay 35 open all of the circuits that were maintained thereby to restore all apparatus in such circuits to normal. The operators telephone equipment is now ready for connection with some new calling subscriber. The previously energized ringing control relay 68 causes the establishment of a circuit traceable from the grounded battery 23, the winding of the sluggishly releasing relay 72, the intermediate armature switch and contact of said relay 68, to ground. The energized relay 72 establishes a circuit for the cutoff relay 25 of the called line, assuming that such line is idle, which is traceable form the grounded two hundred fifty ohm resistance 73, the lower intermediate armature switch of relay 7 2 and its alternate contact,

the third or heel contact of the plug 18 in- 4 tently establishes circuit for the relay 74.

The two armature switches of the ringing relay 75, which in their normal condition establish the continuity of the link section 17, are now attracted to engage their alternate contacts which are connected with the source of ringing current 76 that is thus included in bridge of the line at the called station owing to the engagement of the switch hook thereat with its normal contact. After the called subscriber has responded and during the time that the circuit for the relay 7% is open at the interrupter 75, a circuit is es tablished through the relay 70 owing to the then deenergized condition of the relay 7%. Talking battery is furnished to the called subscriber by way of said relay 70 whose energizing circuit is traceable from the grounded battery 23, the upper winding of relay 70, the top armature switch and contact of relay 72, the top armature switch of relay 74: and its normal contact, the tip of the employed plug 19, the tip spring of the jack 19 engaged by the tip of the plug 18, both sides of the called line and the elevated switch hook, receiver and transmitter at the called station, the sleeve spring of the employed jack 19, the sleeve contact of the plug engaging this spring, the lower armature switch of the relay 74, the normal contact of this switch, the upper intermediate armature switch of relay 72 and the contact engaged thereby, the lower winding of relay 7 O, to ground. The energized relay opens a locking circuit for the relay 68 at the nor mal contact of the armature switch of relay 70, this armature switch then engaging its alternate contact to maintain the obvious circuit through relay 72. The bottom armature switch of the deenergized relay 68 opens the previously traced circuit for the relay 74 so that this relay cannot again be energized, the called subscriber having responded. The calling and called parties are now in telephonic connection by a circuit which will be apparent. lVhen the calling subscriber restores his telephone to its switch hook the switches 9 and 10 that were employed in extending his line are in idle condition all the wiper enrploying switches being preferably of the non-restoring type. When the called subscriber restores his receiver to its switch hook, the relay 70 is deenergized to cause the deenergization of relay 72 whose bottom armature switch establishes a circuit for he clearing out signal lamp 77 whose circuit was partially established at the plug seat switch contact 78 when the plug 18 was removed therefrom in being taken for use. The operator will take down the plug 18 individual to the lamp 77 and restore it into engagement with its plug seat switch 78 thereby effacing the signal conveyed by the lamp 77 whereupon all of the cord equipment pertaining to the restored plug 18 is brought to normal.

If the called line is busy the relay 68 will not be energized when the operator inserts the plug 18 into the jack of the busy wanted line whereupon the busy test relay 69 will be energized by a circuit traceable from the grounded battery 23, the lower winding of the busy test relay 69, the lower intermediate armature switch of relay 72 and its normal contact, the heel of the plug 18, the thimble of the ack engaging the same, the multiple of this jack thimble at the operators position where connection with the busy wanted line has been established, the heel of the plug 18 at such other operators position, the lower intermediate armature switch of energized relay 72 at such other operators position, the alternate contact of this armature switch, to the grounded resistance 73 connected with this alternate contact. Relay 69 pertaining to the link by which connection is sought with the previously busy wanted line is now energized, this relay establishing a circuit for itself traceable from ground, the upper winding of this relay, the bottom armature switch thereof, the alternate contact of this armature switch, the next to the bottom of the armature switches of relay 65, the contact engaged by this armature switch, to the grounded battery 23. The top armature switches of this relay 69 now include the busy tone device 79 in bridge of the line extending to the calling station to indicate to the calling subscriber that the wanted line is busy.

I have indicated at a b commons which extend to the lower armature switches of other relays 35 belonging to other operators. As long as one of these relays 35 is not in use its lower armature switch will engage its normal contact and furnish a driving circuit for the magnet 34 of a switch 12 which serves the switches 11 in the different operators positions. There are two of these switches 11 shown in one operators position, but it is understood that each operator in the exchange has a switch 11 for each group of lines in the exchange, and the switches 12' serve to extend these lines into connection with the idle switch 11 in the idle operators position. When all of the switches 11 in the exchange have been taken for use the driving magnets 3t'belonging to all of the switches 12 will not operate until one of the switches 11 becomes idle whereafter the wipers switch 12 will move into connection with this idle switch 11.

The resistance 67 is common to an operators position and is connected with an idle cord circuit while the operator is building 'maintained through itstwo upper armature switches, this resistance 67 simply being used to prevent a dead ground through the upper winding of 65 while such relay is being energized and looked through the calling partys telephone.

WVhile I have herein shown and particularly described the preferred embodiment of my invention I do not wish to be limited to the precise details of construction and cir cuit arrangement shown as changes may readily be made without departing from the spirit of my invention, but

Having thus described my invention I claim as new and desire to secure by Letters Patent the following 1. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines ineach minor group for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equip ment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extend ing calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches and for bringing calling parties and operators into telephonic connection by way of the employed calling line extending switches and call holding switches; and operator employed switching devices for further extendductors that connect the line extending switches and holding switches.

- 2. A telephone exchange system having telephone lines extending from substations to an exchange and which lines aresubdivided into major groups with the llnes of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in theextension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality ofholding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory 3. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdividedinto major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switches pertaining to the minor group having such master switch; exchange operators" equipment at a plurality of operators positions; a calling line operated distributer switch'for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributerswitch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each ,major group of telephone lines interposed devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

4:. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; a master switch individualto each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators, equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines andcommon to the lines of such major group for associating the equipment or" any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that con nect the line extending switches and holding switches.

5. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivicled into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch .for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

6. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and-less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of op erators positions; a calling line operated distributer switch for each major group of .itiv

telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the hold ing switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and 1 lid call holding switches; and operator em ployed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

7. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; line switches for the telephone lines in each group and less than the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines ofsuch group for associating the equipment of any or" the operators with the calling line employing it; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

8. A telephone-exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of lines and common to the lines of such 'group for associating the equipment of any otthe operators with the calling line employing it; a plurality'of holding switches for each group of telephone lines interposed between'the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and .enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by wav of employed calling line' extending switches and call holding switches; and operatoremployed switching devices for fur ther extending calling lines and individual to the conductors that connect the line ex-v tending switches and holding switches.

9. A telephone exchange system having and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it;

means whereby the calling line operated distributer switch pertaining to each group of lines is limited to the establishment of connection between one o-perators equipment and one calling line; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributor switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means wherebythe holding switches may select and enable the operation of calling line-extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

10. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into 7 groups; exchange operators equipment at a plurality of operators positions; 'a calling line operated distributer switch for each group of lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each group of lines is limited'to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; calling line extending switches for extending calling lines, there being means whereby the holding switches may select. and enable the operation of calling line extending switches, and for bringing calling parties and operators into tele phonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

11. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group for taking part in the extension of calling telephone lines; a mas ter switch individual to each minor group of telephone lines for rendering operative some line switch pertaining .to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory tothe connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

12. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality. of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

13. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of con nection between one operators equipment and one calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

14. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into. major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means wherebythe holding switches may select and enable the operation of call ing line extending switches, and for bringing calling parties and operators into'telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that con nect the line extending switches and holding switches.

15. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the 'major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lincs preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; callingline extending switches for extending calling lines, .there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

16. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extween one operators equipment and one a calling line; a plurality of holding switches for each major group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of call= ing line extending switches; and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that con- .nect the line extending switches and holding with; holding selector switches for transvided into groups; line switches for the telephone lines in each group and less than the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators thereferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

18. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephonic equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches and operator employed switching devices for fur-- ther extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

19. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; line switches for the telephone lines ineach group and less than the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

20. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; exchange operators equipment at a plurality of operators positions; a calling lineoperated distributer switch for each group of lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each group of telephone lines interposed between the calling line operated distributer switches and the operators equipment for holding calling lines preparatory to the connection of the equipment of selected operators therewith; holding selector switches for transferring operators telephone equipment from holding switches to holding switches; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches, and for bringing calling parties and operators into telephonic connection by way of employed calling line extending switches and call holding switches; and operator employed switching devices for further extending call ng lines and individual to the conductors that connect the line extending switches and holding.

switches.

21. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master. switch; exchange operators equipment at a plurality of operators positions; a calling line operated distribute-r switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

22. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdiided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line switch pertaining to the minor group having such master switch; ex change operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each major group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may selectand enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

23. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephonelines in each minor group for taking part in the extension of calling-telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some line swltches pertalning to the. minor group having such master switch; exchange calling line; a plurality of holding switches for each major group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and en able the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

24:. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than'such telephone lines for-taking part in the extension of calling telephone lines; a master switch individual to each minor group of telephone lines for rendering operative some lineswitch pertaining to the minor group having such master switch; exchange operators equipment at a plurality of operators positions; a calling line operated distributor switch for each major group of telephone lines and common to the linesof such major. 5 group for associating the equipment of any ofthe operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each maj or group of telephone lines; calling line ex tending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

25. A telephone exchange system having telephone lines extending from substations to an exchangeand which lines are subdivided into major groups with the lines of the major groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associatingthe equipment of any of the operators and the calling line employing it; a plurality of holding switches for each major group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and in dividual to the conductors that connect the line extending switches and holding switches. i

26. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are divided into major groups with the lines of the ma jor groups divided into minor groups; line switches for the telephone lines in each minor group and less in number than such telephone lines for taking part in the extension of calling telephone lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each major group of telephone lines and common to the lines of such major group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each major group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each maj or group of telephone lines; calling line extending switches for extending calling lines,

there being means whereby the holding switches may select and enable the operation of calling l1ne extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

27. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; line switches for the telephone lines in each group and less than the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

28. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; a plurality of holding switches for each group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches.

29. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdivided into groups; line switches for the telephone lines in each group and less than the number of such lines; exchange operators equipment at a plurality of operators positions; a calling line operated distributer switch for each group of telephone lines and common to the lines of such group for associating the equipment of any of the operators with the calling line employing it; means whereby the calling line operated distributer switch pertaining to each group of lines is limited to the establishment of connection between one operators equipment and one calling line; a plurality of holding switches for each group of telephone lines; calling line extending switches for extending calling lines, there being means whereby the holding switches may select and enable the operation of calling line extending switches; and operator employed switching devices for further extending calling lines and individual to the conductors that connect the line extending switches and holding switches.

30. A telephone exchange system having telephone lines extending from substations to an exchange and which lines are subdi- 

